[PATCH v2 7/7] builtin/clone: create the refdb with the correct object format
- From
Patrick Steinhardt <ps@pks.im>
- Date
- Dec 12, 2023, 07:01 UTC
- Message-ID
- <f062b11550a559fb0c96ef0fa188110f6116e3c6.1702361370.git.ps@pks.im>
- In-Reply-To
- <cover.1702361370.git.ps@pks.im>
We're currently creating the reference database with a potentially incorrect object format when the remote repository's object format is different from the local default object format. This works just fine for now because the files backend never records the object format anywhere. But this logic will fail with any new reference backend that encodes this information in some form either on-disk or in-memory.
The preceding commits have reshuffled code in git-clone(1) so that there is no code path that will access the reference database before we have detected the remote's object format. With these refactorings we can now defer initialization of the reference database until after we have learned the remote's object format and thus initialize it with the correct format from the get-go.
These refactorings are required to make git-clone(1) work with the upcoming reftable backend when cloning repositories with the SHA256 object format.
This change breaks a test in "t5550-http-fetch-dumb.sh" when cloning an empty repository with `GIT_TEST_DEFAULT_HASH=sha256`. The test expects the resulting hash format of the empty cloned repository to match the default hash, but now we always end up with a sha1 repository. The problem is that for dumb HTTP fetches, we have no easy way to figure out the remote's hash function except for deriving it based on the hash length of refs in `info/refs`. But as the remote repository is empty we cannot rely on this detection mechanism.
Before the change in this commit we already initialized the repository with the default hash function and then left it as-is. With this patch we always use the hash function detected via the remote, where we fall back to "sha1" in case we cannot detect it.
Neither the old nor the new behaviour are correct as we second-guess the remote hash function in both cases. But given that this is a rather unlikely edge case (we use the dumb HTTP protocol, the remote repository uses SHA256 and the remote repository is empty), let's simply adapt the test to assert the new behaviour. If we want to properly address this edge case in the future we will have to extend the dumb HTTP protocol so that we can properly detect the hash function for empty repositories.
Signed-off-by: Patrick Steinhardt <ps@pks.im> --- builtin/clone.c | 9 ++++++++- setup.c | 2 +- setup.h | 1 + t/t5550-http-fetch-dumb.sh | 4 ++-- 4 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/builtin/clone.c b/builtin/clone.c index 06966c5d4c..fd052b8b54 100644 --- a/builtin/clone.c +++ b/builtin/clone.c @@ -1097,8 +1097,14 @@ int cmd_clone(int argc, const char **argv, const char *prefix) } } + /* + * Initialize the repository, but skip initializing the reference + * database. We do not yet know about the object format of the + * repository, and reference backends may persist that information into + * their on-disk data structures. + */ init_db(git_dir, real_git_dir, option_template, GIT_HASH_UNKNOWN, NULL, - do_not_override_repo_unix_permissions, INIT_DB_QUIET); + do_not_override_repo_unix_permissions, INIT_DB_QUIET | INIT_DB_SKIP_REFDB); if (real_git_dir) { free((char *)git_dir); @@ -1282,6 +1288,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix) hash_algo = hash_algo_by_ptr(transport_get_hash_algo(transport)); initialize_repository_version(hash_algo, 1); repo_set_hash_algo(the_repository, hash_algo); + create_reference_database(NULL, 1); /* * Before fetching from the remote, download and install bundle diff --git a/setup.c b/setup.c index d6a1c59b7b..155fe13f70 100644 --- a/setup.c +++ b/setup.c @@ -1897,7 +1897,7 @@ static int is_reinit(void) return ret; } -static void create_reference_database(const char *initial_branch, int quiet) +void create_reference_database(const char *initial_branch, int quiet) { struct strbuf err = STRBUF_INIT; int reinit = is_reinit(); diff --git a/setup.h b/setup.h index cbf538286b..3f0f17c351 100644 --- a/setup.h +++ b/setup.h @@ -178,6 +178,7 @@ int init_db(const char *git_dir, const char *real_git_dir, const char *initial_branch, int init_shared_repository, unsigned int flags); void initialize_repository_version(int hash_algo, int reinit); +void create_reference_database(const char *initial_branch, int quiet); /* * NOTE NOTE NOTE!! diff --git a/t/t5550-http-fetch-dumb.sh b/t/t5550-http-fetch-dumb.sh index e444b30bf6..4c3b32785d 100755 --- a/t/t5550-http-fetch-dumb.sh +++ b/t/t5550-http-fetch-dumb.sh @@ -66,11 +66,11 @@ test_expect_success 'create empty remote repository' ' setup_post_update_server_info_hook "$HTTPD_DOCUMENT_ROOT_PATH/empty.git" ' -test_expect_success 'empty dumb HTTP repository has default hash algorithm' ' +test_expect_success 'empty dumb HTTP repository falls back to SHA1' ' test_when_finished "rm -fr clone-empty" && git clone $HTTPD_URL/dumb/empty.git clone-empty && git -C clone-empty rev-parse --show-object-format >empty-format && - test "$(cat empty-format)" = "$(test_oid algo)" + test "$(cat empty-format)" = sha1 ' setup_askpass_helper
-- 2.43.GIT